View Compilation Error

0_0_29340209_23298.cpp: In function 'll pow_mod(ll, ll)':
0_0_29340209_23298.cpp:11:12: error: 'k' was not declared in this scope
     while (k){
            ^
0_0_29340209_23298.cpp:12:27: error: 'n' was not declared in this scope
         if (k&1) res=(res*n)%mod;
                           ^
0_0_29340209_23298.cpp:12:30: error: 'mod' was not declared in this scope
         if (k&1) res=(res*n)%mod;
                              ^
0_0_29340209_23298.cpp:13:9: error: 'n' was not declared in this scope
         n=n*n;
         ^